Step 1

Add the oil, peanut butter, sugar & egg yolk to a large mug. Whisk together until smooth.

Step 2

Whisk in the flour and baking powder.

Step 3

Stir in the milk and optional chocolate chips

Step 4

Microwave for 1 minute and 30 seconds or until the top looks set.

Step 5

Let stand for 1-2 minutes to cool slightly, then top with ice cream or a drizzle of peanut butter.